1. Field of the Invention
The present invention relates to a video/audio outlet in a video/audio player, and more particularly to a detection device and method commonly used for video and audio outlets in a carry type recorder/player or carry type player.
2. Description of Related Art
The video/audio output interface of a general carry type video recorder/player and video player is shown in FIG. 1. The interface comprises a four-terminals outlet 10 and a corresponding circuit structure 20. The outlet 10 includes a ground terminal 11, video output terminal 12, first audio output terminal 13 and second audio output terminal 14, which are contacted respectively with a ground terminal 31, video input terminal 32, first audio input terminal 33 and second audio input terminal 34 of the video/audio four-terminals plug 30 shown in FIG. 2. The first audio output terminal 13 is connected to a push rod 15. The push rod 15 can be pushed simultaneously to separate a detection line 16 from a ground line 17 when the plug 30 is inserted to touch the first audio output terminal 13. A video signal output terminal 21, second audio signal output terminal 22, first audio signal output terminal 23 and plug detection terminal end 24 of the circuit structure 20 are communicated respectively with the video output terminal 12, the second audio output terminal 14, the first audio output terminal 13 and the detection line 16 of the outlet 10.
At present, a general video/audio device has an earphone three-terminals outlet and video four-terminals outlet respectively. Please refer to FIGS. 2 and 3. A three-terminals earphone plug 40 and four-terminals video plug 30 must be inserted in a commonly used four-terminals outlet in order to reduce the volume of video/audio device that appears smaller and smaller. The most commonly used method is to revise the structure of a outlet so as to be able to judge what kind of plug is inserted when it must be used commonly. Otherwise, a plug must be furnished with multiple of respective output lines. But, if a standard earphone plug with a 3.5 φ or 2.5 φ diameter is still be used, the outlet revise is impractical. The only way we can do is to use the four-terminals outlet of the standard insertion holes, and then to operate in cooperation with the output mode of the manual operation system. For example, a video/audio device with such as the four-terminals outlet 10 shown in FIG. 1 for the common output of a video output and audio output is already existed in the market. But, a user must choose whether to output a video signal simultaneously by using the manual operation system. The user must choose not to output a video signal and shut off an in built horn device when the three-terminals earphone outlet 40 is inserted. On the other hand, the user must not only choose outputting a stereo audio signal and shutting off the in built horn device but also allowing the system to output a video signal if the four-terminals video plug 30 is inserted. The operation for switching output modes mentioned above rather wastes time, it is inconvenient for a user that is not familiar with the output modes switching. The first audio input terminal 41 and the second audio input terminal 42 of the plug 40 are contacted respectively with the first audio output terminal 13 and the second audio output terminal 14 when the plug 40 is inserted. But, the ground terminal 43 of the plug 40 is contacted at the same time with the ground terminal 11 and the video output terminal 12 of the outlet 10. A video signal is transmitted continuously to the video output terminal 12 and consequently to the ground terminal 11 if the video signal output is not stopped. This is only wastes electricity but also might damage the parts in a circuit.